The invention relates to a washing machine capable of efficiently washing all kinds of laundry, having a wash basket with varying load capacities and operating with differing wash water levels in the tub.
U.S. application, Ser. No. 677,302, filed Dec. 3, 1984 describes a washing machine comprising a wash tub, a wash basket, and a housing for collecting the wash water placed in a position beneath and connected to the tub. The housing is profiled so as to contain at least one filter element, one electric heating element and one thermostatic sensor capable of, respectively, filtering, heating, and sensing the temperature of the wash water.
This housing is connected both to the discharge hose of the washing machine by means of a conventional draining pump and to the wash tub by means of another hose. An electric recirculation pump is spaced a distance from, or concentrically with, the draining pump. The electric recirculation pump has an intake hose connected to the housing and a delivery hose connected to the tub.
The washing machine disclosed in U.S. application, Ser. No. 677,302 is suitable for conventional "vigorous" and "delicate" type laundering operations for washing heavily soiled articles of clothing. The wash cycles are performed with normal filling levels of the wash water in the tub while keeping the electric recirculation pump turned off throughout the duration of the wash cycles. The "vigorous" laundering operations for washing lightly soiled items are carried out with low filling levels of the wash water in the tub and switching on the electric recirculation pump during predetermined periods of the wash cycles in order to circulate the wash water repeatedly from the housing to the tub.
In particular, these latter "vigorous" laundering operations with low filling levels of wash water result in a remarkable lowering of the consumption of water, detergents, and electrical energy when compared to wash cycles of conventional washing machines.
Moreover, the washing machine disclosed in U.S. application, Ser. No. 677,302 is equipped with a first and second series of pressure switches or similar water-level regulators associated with, respectively, the "vigorous" laundering operations for low filling levels, and the "vigorous" laundering operations for normal water levels in the tub. These pressure switches are switched on one-by-one by means of the corresponding manually-operated switches before the start of every wash cycle, depending on the particular load placed in the basket.
For example, the first series consists of three pressure switches for laundering, respectively, a full, a half, and a quarter, of a wash load, while the second series consists of two pressure switches for laundering, respectively, a full, and a half wash load. This washing machine also has another pressure switch calibrated for a filling level of the wash water in the tub which is different from the prior art pressure switches and enables the "delicate" laundering operations, such as for delicate synthetic fabrics and/or woolens.
However, a washing machine as described above, despite its satisfactory and reliable operation, has the disadvantage of requiring a considerable number of pressure switches or similar water-level regulators in order to determine preset filling levels of the wash water in the tub which correspond to the loads placed in the basket.
Furthermore, in order to carry out each laundering operation in the washing machine discussed above, it is necessary for an operator to manually selectively actuate the pressure switches. These pressure switches can also be used to carry out laundering operations of the type described earlier, but with loads in the wash basket differing from full, half and quarter wash loads. In these instances, it is possible to wash the load efficiently, but without optimum consumption of water, electric energy and detergents.